Most of the heat inside a passivhaus comes from the occupants (we give off a surprising amount of heat) and what they do. All the heat from showering, cooking, laundry and all the appliances is used to heat the house along with the sun in the colder months. The heat recovery ventilation system then ensures you always have fresh air in the house but it recovers around 90% of the heat from the stale air it’s extracting. So, you lose very little heat. Our own passivhaus home stays at around 21-23 degrees celsius and last year cost us £50 (GBP) to heat it, which equates to £0.13p per square metre for the whole year. Contact us if you'd like to know more.